Real time optical monitoring of molecular beam epitaxy of InN on SiC substrates

Spectroscopic ellipsometry has been used to monitor in real time and in situ the molecular beam epitaxial growth of InN on SiC substrates. A three-step growth process consisting of (i) low-temperature $(200°C)$ nitridation of the SiC surface, (ii) low-temperature $(350°C)$ nucleation of a thin InN buffer layer, and (iii) growth of the InN epitaxial layer at $450°C$ has been applied. The impact of the In flux on the growth kinetics, morphology, and structural and optical properties of InN has been investigated. It is found that independent of the In flux the low-temperature buffer shows In surface accumulation. This In surface accumulation increases during InN growth under In-rich conditions and is depleted during growth under intermediate and N-rich conditions. Better structural, morphological, and optical properties are obtained when the films are grown under In-rich conditions.